1Department of Otolaryngology–Head and Neck Surgery, New York University School of Medicine, New York, New York, USA2Department of Otolaryngology–Head and Neck Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA3Department of Radiology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA4Biostatistics Facility, UPMC Hillman Cancer Center, Pittsburgh, Pennsylvania, USA

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Abstract

ObjectiveTo compare positive margin rates between the 2 most common subsites of oropharyngeal transoral robotic surgery (TORS), the base of tongue (BOT) and the tonsil, as well as identify preoperative imaging characteristics that predispose toward positive margins.Study DesignCase series with chart review.SettingTertiary care referral center.Subjects and MethodsWe compared the final and intraoperative positive margin rate between TORS resections for tonsil and BOT oropharyngeal squamous cell carcinoma (OPSCC), as well as the effect of margins on treatment. A blinded neuroradiologist examined the preoperative imaging of BOT tumors to measure their dimensions and patterns of spread and provided a prediction of final margin results.ResultsBetween January 2010 and May 2016, a total of 254 patients underwent TORS for OPSCC. A total of 140 patients who underwent TORS for T1/T2 OPSCC met inclusion criteria. A final positive margin is significantly more likely for BOT tumors than tonsil tumors (19.6% vs 4.5%, respectively, P = .004) and likewise for intraoperative margins of BOT and tonsil tumors (35.3% vs 12.4%, respectively; P = .002). A positive final margin is 10 times more likely to receive chemoradiation compared to a negative margin, controlling for extracapsular spread and nodal status (odds ratio, 9.6; 95% confidence interval, 1.6-59.6; P = .02). Preoperative imaging characteristics and subjective radiologic examination of BOT tumors did not correlate with final margin status.ConclusionPositive margins are significantly more likely during TORS BOT resections compared to tonsil resections. More research is needed to help surgeons predict which T1/T2 tumors will be difficult to completely extirpate.